Transmission



April 14, 1964 'M. E. FISHER ETAL 3,128,642

4 TRANSMISSION.

Fi led Dec. 5, 1960 'r Sheets-Sheet 1 April 1964 M. E. FISHER ETAL 3,128,642

TRANSMISSION Filed Dec. 5, 1960 7 SheetT-Sheet 2 ATTOPA/EY April 14, 1964 M. E. FISHER ETAL 3,128,642

TRANSMISSION Filed Dec. 5, 1960 7 Sheets-Sheet INVE/V T0195 Attorney April 14, 1964 Filed Dec. 5, 1960 M. E. FISHER ETAL TRANSMISSION 7 Sheets-Sheet 4 AT TORNE Y A ril 14, 1964 M. E. FISHER ETAL TRANSMISSION 7 Sheets-Sheet 6' Filed Dec. 5, 1960 awn/roe:

ATTOQNEY" Apnl 14, 1964 M. E. FISHER ETAL 3,123,642

TRANSMISSION Filed Dec. 5, 1960 7 Sheets-Sheet 7 Mme/var United States Patent i if 3,128,642. TRANSMISSION Mark E. Fisher, Carmel, Sidney A. Rains, Speedway City,

and William B. Clark, Greenwood, Ind, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Dec. 5, 1960, Ser. No. 73,564 39 Claims. (Cl. 74752) This invention relates to an automatic transmission and more particularly to a control system for a transmission having a torque converter, a lockup clutch and a multiratio gear unit.

The transmission drive train includes a torque converter and lockup clutch unit, a hydrodynamic brake and a six-speed and reverse gear unit. The gear unit includes a two-speed splitter unit and a three-speed and reverse unit. The control system is manually controlled for operation in a plurality of ranges in which the automatic control system will control the transmission gearing to provide a drive in certain ratios in accordance with transmission speed and throttle pedal position. This application is an improvement over the assignees copending application S.N. 554,866, entitled Transmission, filed December 22, 1955, by Howard W. Christenson, Mark E. Fisher and Edward T. Mabley, and application S.N. 731,047, now US. Patent No. 3,053,116, entitled Transmission, filed April 25, 1958, by Howard W. Christensen, Mark E. Fisher, Robert H. Schaefer, William B. Clark and Sidney A. Rains.

The transmission is controlled by the operator selectively placing the selector valve in the desired range position. The selector valve by means of a plurality of range signal pressures controls the operation of the ratio shift valves to provide a specific limited range of ratios in each range of transmission operation. This transmission provides for selection of a reverse range providing two reverse ratios, 2. neutral range providing a positive neutral, a drive range providing automatic shifting be tween third and sixth ratios, a fifth gear hold range providing automatic shifting between third and fifth ratios, an intermediate range providing automatic shifting between third and fourth ratios and a low range providing automatic shifting between the first and second ratios, as in the above application S.N. 731,047, now US. Patent No. 3,053,116. In reverse range, reverse in the threespeed unit and underdrive or direct in the splitter unit are engaged to provide two reverse ratios. In low range a splitter shift valve automatically controls the two-speed unit to provide first and second ratios in conjunction with low ratio in the three-speed unit. In intermediate range the low intermediate shift valve is shifted to engage intermediate ratio in the three-speed unit and the splitter shift valve is controlled by governor and throttle to provide third and fourth ratios. In drive range, third and fourth ratios are provided as in intermediate range and the intermediate high shift valve is controlled by governor and throttle to upshift the three-speed unit to high ratio in conjunction with modified splitter shift valve control to provide fifth or sixth ratios. In fifth gear hold range, which is desirable under some driving conditions requiring performance or during the operation of the hydrodynamic brake, the splitter shift valve is held in splitter low so that only third, fourth and fifth ratios are available.

The main regulator valve for the fluid supply of this control system regulates the pressure at levels varied by the throttle pedal position, the splitter high and intermediate clutch pressures, the lockup pressure and the hydrodynamic brake pressure. In addition, during the application of each ratio engaging device, the fluid pressure is regulated by a trimmer valve which initially re- 3,128,642 Patented Apr. 14, 1964 duces the pressure to a throttle modulated value and then permits a slow controlled increase of pressure controlled by the pressure in the ratio engaging line to increase this pressure to main line pressure. The lockup clutch is also disengaged by the lockup cutoff valve during each engagement of the ratio engaging device and on re-engagement of the lockup clutch the trimmer valve is positively reset for another regulating cycle.

The controls for supplying fluid to the torque converter and the hydrodynamic brake are inter-related and controlled by the hydrodynamic brake control valve to provide an auto-circulation supply system for the torque converter when the brake is off and to terminate this supply system and provide an auto-circulation supply system for the hydrodynamic brake when the brake is applied. When the hydrodynamic brake control valve is moved from the brake otf position to the brake apply position, the torque converter outlet flow will continue to pass through the cooler until the brake outlet flow rises to a higher pressure. The cooler outlet flow is connected to the brake control valve and may be supplemented by main line pressure from the front and rear transmission pumps and is connected to the brake inlet to supply fluid through the hydrodynamic brake. When the brake valve is moved to the off position, the brake outlet flow is exhausted and the converter outlet flow is passed through the cooler to the brake control valve. The brake control valve connects this cooler outlet flow to the feed line which previously supplied oil to the brake. The converter outlet fluid now flows in the reverse direction through this feed line and through the fluid pressure supply system to the lockup clutch valve which controls the flow of fluid to supply the converter.

The torque converter lockup clutch and multiratio transmission unit controls are inter-related so that the first shift from first to second ratio under the influence of governor and throttle pedal position cannot occur until the lockup clutch has been initially engaged by the up shift of the lockup clutch valve under the influence of governor and throttle pressures. This is accomplished by employing the lockup pressure to remove a disabling plug from engagement with first to second ratio shift valve.

In this combination there is also a lockup cutoff valve which functions in response to each ratio shift to cut off the lockup clutch fluid supply from .the lockup shift valve to the lockup clutch for the duration of each ratio change. In order to insure that the ratio change has been completed for a predetermined time before the lockup clutch is re-engaged after a ratio shift, a time delay device, such as an accumulator, is provided in connection with the lockup cutoff valve to delay the rate of return movement of the valve to the open position to' delay re-engagement of the lockup clutch after the shift has terminated.

An object of the invention is to provide in a transmission having a torque converter and a hydrodynamic brake, a fluid pressure supply and control system including a brake control valve operative to control the engagement and the disengagement of the hydrodynamic brake and to provide in a brake disengaged position an auto-circulation type fluid supply for the torque converter.

Another object of the invention is to provide in a transmission having a torque converter and a hydrodynamic brake, a fluid pressure supply and control system including a brake control valve operative; to control the engagement and the disengagement of the hydrodynamic brake and to provide in a brake disengaged position an auto-circulation type fluid supply for the torque converter and in the brake engaged position an auto-circulation type fluid supply for the hydrodynamic brake.

Another object of the invention is to provide in a transmission including a torque converter, a lockup clutch and a multiratio gear unit, a control system including a lockup clutch control for engaging the lockup clutch, a lockup cutoff control for disengaging the lockup clutch for the duration of a ratio change and a time delay device to delay the re-engagement of the lockup clutch for a predetermined period after the engagement of the ratio.

Another object of the invention is to provide in a multiratio transmission having a fluid actuated ratio engaging device, a pressure regulator valve operative in response to the engagement of the ratio to reduce the initial pressure value to a lower value variable in accordance with a torque demand signal and to increase the pressure at a gradual rate to complete engagement of the ratio device.

Another object of the invention is to provide in a multiratio transmission, a control system having a shift valve for selectively engaging one ratio and disengaging another ratio, an exhaust valve operative to continue to supply full line pressure to the ratio being disengaged until the pressure in the ratio device being engaged attains a predetermined value.

Another object of the invention is to provide in a transmission including a torque converter, a lockup clutch and a rnultiratio gear unit, a control system including a ratio shift control for selectively engaging higher ratios with increasing speed, a lockup clutch control for engaging the lockup clutch, and an inter-control normally disabling the ratio shift control and operative in response to engagement of the lockup clutch to render the shift control operative.

Another object of the invention is to provide in a multiratio transmission having a torque converter, lockup clutch and fluid actuated ratio engaging device, ratio control means to selectively establish ratios, a lockup control to engage the lockup clutch and a lockup cutoff valve operative for the duration of a ratio change to disengage the lockup clutch and to render operative a pressure regulator valve operative in response to the engagement of the ratio to reduce the initial pressure value to a lower value variable in accordance with a torque demand signal and to increase the pressure at a gradual rate to complete engagement of the ratio device.

These and other objects of the invention will be more apparent from the following description and drawings of the preferred embodiment of the invention.

The drawing diagrammatically shows the transmission and control system with FIGURES 2, 3, 4, 5, 6 and 7 arranged in accordance with the schematic diagram shown in FIG. 1. FIG. 8 illustrates a modification of a portion of the hydraulic control system.

Transmission Drive Train The drive train illustrated diagrammatically in FIG. 2 includes a torque converter and lockup clutch unit 10, a hydrodynamic brake 25, and a six-speed and reverse gear unit 20. The engine or input shaft 1 is connected to drive the rotary torque converter housing 2 which carries the bladed pump or impeller 3 of the torque converter 4. The torque converter pump hydrokinetically drives the bladed turbine 6 which is mounted by disc 7 on the converter output shaft 8. The torque converter 4 also has two stators 9 which may be mounted by suitable oneway devices (not shown) on the ground sleeve 11. Fluid is supplied to the operating chamber of the converter by the converter inlet line 160 and exhausted by the outlet line 101 which are connected to the control system as explained below. The torque converter 4 provides in a conventional manner a shockless torque multiplying drive between the input shaft 1 and converter output shaft 8.

The input shaft 1 may also be connected to the converter output shaft 8 by the direct drive or lockup clutch 16. The direct drive clutch 16 consists of a fixed plate 17 mounted on the rotary housing 2 and an axially movable plate 18 formed as a face of the annular piston 19 non-rotatably located in the cylinder 21. The driven plate 22 is located between the fixed plate 17 and the movable plate 18 and connected by disc 7 to shaft 8. When fluid is supplied through the lockup clutch line to the servo motor consisting of piston 19 and cylinder 21, the driven clutch plate 22 is engaged between the movable plate 18 and fixed plate 17 to engage the direct drive clutch 16.

The converter output shaft 8 is connected by disc 23 to drive the rotary vanes 24 of hydrodynamic brake 25 and the input ring gear 26 of splitter gear unit 27. The rotary vanes 24 of hydrodynamic brake 25 are located between two rows of fixed vanes 28 mounted within the brake chamber at each side of the rotary vanes. Fluid is supplied to the hydrodynamic brake chamber by inlet line 186 which is connected to the center of the brake and removed from the brake by the outlet line 181 which is connected at the perimeter of the brake chamber. The centrifugal action of the brake provides an outlet line pressure proportional to the torque absorbed by the brake due to the location of the outlet at the radial outer region of the brake chamber.

The converter output shaft 8 drives the input ring gear 26 of the planetary splitter gear unit 27 which meshes with planetary pinions 31 which are mounted on a carrier 32 secured to the connecting shaft 33. The splitter gear unit 27 is controlled by the sun gear 34 which meshes with the planetary pinions 31. To provide low or underdrive, the sun gear 34 is held by the brake or ratio engaging device 35 when actuated by motor 36 which, like all the motors in this transmission, consists of a piston and cylinder. The motors or the associated brakes or clutches for each ratio engaging device may have conventional retraction springs (not shown). The motor 36 is actuated by fluid supplied by the splitter underdrive line 150. The splitter unit 27 is placed in high or direct drive by engaging the clutch or ratio engaging device 38 which fixes the sun gear 34 to the connecting shaft 33. The clutch 38 is engaged by the motor 39 when fluid is supplied by the splitter direct line 170.

The splitter gear unit 27 is connected by the connecting shaft 33 to the three-speed and reverse planetary gear unit 46. The connecting shaft 33 is connected by driving element 47 to the high clutch or ratio engaging device 48 which is actuated by the high motor 49 supplied by the high ratio line 210.

The front Pitot tube governor 51 has a can mounted on driving element 47 and a Pitot tube on the housing to supply fluid to the front Pitot governor line 220 at a pressure proportional to the speed of the splitter gear output or connecting shaft 33. The high clutch 48 rotates with element 47 and connects the driving element 47 to the carrier assembly 56. The carrier assembly includes the intermediate planetary pinions 57 which mesh with the intermediate sun gear '58 fixed to shaft 33 and inter mediate ring gear 59. To provide intermediate ratio, the mtermediate ring gear 59 is stopped by ratio brake or ratio engaging device 61 when actuated by the intermediate motor 62 under the control of fluid supplied by the intermediate clutch line 250. The carrier assembly 56 also includes the low ring gear 66 which meshes with the planetary pinions 67 mounted on carrier 68 fixed to output shaft 69. The low sun gear 71 fixed to shaft 33 meshes with planetary pinions 67. Low ratio is provided by stopping the ring gear 66 and incidentally the carrier assembly 56, by means of the low ratio brake or ratio engaging device 72 which is actuated by the motor 74 when pressure is supplied by the low clutch line 270.

The carrier assembly 56 also includes the reverse sun gear 76 which meshes with the reverse pinions 77 rotatably mounted on carrier 73 fixed to output shaft 69. The reverse ring gear 79 is held stationary for reverse drive by ratio brake or ratio engaging device 81 when engaged by .5 motor 83 on the supply of fluid by the reverse clutch line 310.

The rear Pitot governer 86 has a can mounted on carrier 78 to rotate with the output shaft 69 and a Pitot tube fixed on the housing to supply the rear governor line 328 with a pressure proportional to output shaft speed.

Transmission Gearing Operation This gearing arrangement provides six forward speed ratios and two reverse ratios by combining the two-speed ratios of the two-speed or splitter gear unit 27 and the three ratios and reverse of the three-speed and reverse unit 46. The splitter gear unit 27 has an input ring gear driven by the torque converter 4. When ratio device 35 is engaged to stop sun gear 34, the output pinions 31 and shaft 33 are driven at a reduced speed or underdrive ratio. When clutch 33 locks sun gear 34 to connecting shaft 33, the splitter gear is locked up to provide a high ratio or direct drive. The three-speed unit provides low ratio when the low ratio device 72 is engaged to hold low reaction ring gear 66 so that the input sun gear 71 drives pinions 67 and output shaft 69 at a reduced speed for low ratio. When intermediate ratio device 61 is engaged, the three-speed unit functions as a dual planetary gear. The intermediate reaction ring gear is held and the input sun gear 58 drives carrier 56 which rotates low ring gear 66 to drive, in conjunction with input sun gear 71, the output pinions 67 and shaft 69 at an intermediate ratio. High ratio is provided by engaging the high ratio device 4-8 to lock the carrier 56 to connecting shaft 33 to lock up the three-speed unit for direct drive or high ratio. Each of the six ratios is provided by engaging one ratio in the splitter gear unit 27 and one ratio in the three-speed unit and disengaging the other ratios. When the low ratio device 72 is engaged to provide low ratio in the three-speed unit 46, the transmission may be placed in either first ratio by placing the splitter gear unit 27 in underdrive by engaging device 35 or in second ratio by placing splitter gear unit 27 in direct drive by engaging device 33. When the three-speed unit 46 is placed in intermediate ratio by engaging device 61, the transmission may similarly be placed in third and fourth ratios by again engaging the underdrive or the direct drive respectively of the splitter gear unit 27. When the transmission is shifted to high ratio in the three-speed unit 46, the transmission may be placed in fifth ratio by shifting the splitter gear unit to underdrive and sixth ratio by shifting the splitter gear unit to direct drive. When the transmission is in reverse, the splitter unit may be upshifted to provide reverse one (R1) and reverse two (R2).

Controls The hydraulic control and lubrication system for this transmission is supplied with oil under pressure by the engine driven front pump 166 and output shaft driven rear pump 321 (FIG. 7). The front pump 166 draws the fluid, such as oil, via inlet line 326 from the transmission sump and is connected to deliver oil through the front pump line 327. The rear pump 321 draws oil from the sump through the inlet line 328 and is connected to deliver oil to the rear pump line 329. An orifice bleed 331 in line 329 feeds the rear governor can 311 and regulates the pressure in the rear pump line 329 so that it is proportional to pump speed and thus output shaft or vehicle speed to provide a second output speed responsive governor pressure. The rear pump 321' is primed by an orificed connection 332 (FIG. between the front pump supply line 327 and rear pump line 329.

Referring to FIG. 5, the front pump line 327 is connected through the housing of check valve 333 and the rear pump line 329 is connected through ball check valve 336 to the bore of valve 333 which is connected to main line 340 to permit either pump to supply oil to the control system. The pressure in main line 340 is regulated by pressure control unit 341.

Cir

6 Pressure Control Unit The pressure control unit 341 consists of a regulator valve 343 which is controlled by a throttle pressure regulator plug 346, brake regulator plugs 347 and 348 and lockup knockdown plug 349. Regulator valve 343 has a large land a at the upper or exhaust end, a large central land b and smaller lands c and d at the other end. The lands a and b fit in the large diameter portion 351 of the valve bore located above the port 352 for main line 341). The lands a and d fit in the smaller diameter bore portion 353 located below the port 352. The land d has an orifice 344 or a clearance in the bore to permit limited fiow past the land. The main line 340 is always open via the port 352 through the valve. When the valve is in the closed position, as illustrated in FIG. 5, the land b closes port 355 for the secondary line 356 which feeds the converter and brake. Oil supplied by the main line 340 fills the space between the unbalanced lands b and c and tends to move the valve up to uncover the port 355 to supply oil to the line 356. The port 358 located between the balanced lands a and b of valve 343 is connected to the front pump line 327. The port 358 is long and has intermediate its length a guide 359 which has slots to provide fluid communication between the two portions of the port. The oil in port 353 acts on the balanced areas a and b and thus does not tend to move the valve. With the valve in the closed position shown, the exhaust from port 358 to port 361 is blocked by land a, but in exhaust position line 327 is connected via port 358 to port 361. The exhaust from port 361 is connected to low pressure line 362 to provide a low pressure feed for the converter when the converter is not multiplying torque and the lockup valve 445 (FIG. 5) has moved to engage the lockup clutch 16. A low pressure is maintained in the port 361 by the pressure relief valve 363 which controls the exhaust from port 361. In valve unit 341 above regulator valve element 343 there is a spring chamber 366 which provides an abutment at one end for dual spring 367 acting upon the free end of the land 343a to urge the valve 343 toward the closed position against the fluid force acting on the unbalanced area of lands b and c.

When the oil in main line 346 between the unbalanced areas between lands b and c raises valve 343, the first increment of movement permits flow of oil to port 355 and secondary line 356. When the pressure in the main and secondary lines has reached a desired value, the valve will raise and land a opens the port 361 and connects the front pump line 327 through port 358 directly to exhaust port 361 to supply the low pressure feed line 362 and exhaust excess oil through the pressure relief valve 363 to sump.

The regulated pressure in main line 340 is increased by the hydrodynamic brake pressure and the throttle valve pressure. The brake outlet pressure which is proportional to the torque being absorbed by the brake is conveyed by line 181 to spring chamber 366 and acts on the free end of land a of valve 343 to assist the spring 367 to increase the regulated line pressure. The throttle plug 346 fits in the small end bore portion 382. The throttle pressure, which is a pressure proportional to the throttle pedal position as explained below in the description of the throttle valve unit 461 (FIG. 6), is supplied by line 468 to the bore portion 332 to act downwardly on the plug 346 and pressure regulator valve 343 assisting spring 367 and thus increasing the pressure in main line 340. An orifice 383 in the throttle line 468 connected to bore 362 damps and delays sudden variations in throttle pressure to prevent rapid changes in main line pressure. The plug 346 provides a stop to limit the upward movement of valve 363. When the brake pressure supplied by line 181 to spring cavity 366 increases the regulated pressure in line 346 by acting in a downward direction on the free end of land a of valve 343, the brake pressure also acts upwardly on the plug 346 and partially or fully counteracts the pressure increasing effect due to the throttle pressure on plug 346 to prevent an excessive increase in main line pressure. However, during normal operation, the throttle will be closed when the brake is applied so there will not be any throttle pressure. As explained below, the brake pressure also acts on the smaller area of plug 347 to decrease the main line pressure providing a net pressure increasing effect of a small value without employing a small land.

The main line pressure is reduced by the splitter high clutch pressure, brake pressure and the lockup pressure from the governor and throttle controlled lockup valve unit 445 (FIG. 5). With valve 343 in the closed position in FIG. 5, the bore 353 has a port 388, immediately below the land c, connected to the splitter high line 1'70. The brake regulator plug 347 is located between the port 388 and the port 389 connected to brake outlet line 181. The brake regulator sealing plug 348 is located below plug 347 between port 389 and exhaust port 391. The lockup knockdown plug 349 below the plug 343 has a small diameter land a abutting the sealing plug 348 and a larger diameter land b at the other end. The bore 353 has a seal 393 adjacent the exhaust port 391 engaging the small diameter land 349a and a large diameter bore portion 394 in which the land 34% slides. The intermediate clutch line 25b is connected to the bore 394 below seal 393 to act down on the large land I) to urge the plug 349 down to the inactive position. The controlled lockup clutch oil in line 395 is connected to the closed end of the large bore 394 to act up on the free end of land b of plug 349.

The splitter high clutch pressure in line 170 acts on the land c of regulator valve 343 to oppose spring 367 and lower the regulated main line (3%) pressure and on both sides of land a through communicating orifice 34-4 to damp the action of the splitter high pressure on the regulator valve 343 and movement of the regulator valve 343. The brake outlet pressure in line 131 acts upon the lower end face of plug 347 to oppose the spring 367 and reduce the regulated pressure. As pointed out above, the brake pressure simultaneously acts on the larger area of land 343a and the smaller area of plug 347 to provide a net increase of main line pressure. This differential arrangement reduces the effect of high brake pressure on valve 343 without employing an extremely small valve plug. The governor controlled lockup clutch pressure in feed line 395 acts upon the lower face of plug 349 against the spring 367 to reduce line pressure. Thus each of these pressures acts against the spring 367 and to lower main line pressure. Since the plugs are arranged in series, the effective force on the regulator valve 3 .3 to move it toward the open position against the spring 367 will only be as large as the largest of these three fluid forces acting on their respective plugs. The intermediate clutch pressure in line 253- acts on the plug 349 with the spring 367 but is only effective to oppose the pressure in feed line 395 acting up on plug 34-9 to partially reduce the effect of this pressure so that the governor controlled lockup pressure will not reduce the regulated line pressure as much in intermediate ratio as in other ratios.

Throttle Valve Unit The throttle valve unit 401 (FIG. 6) supplies a throttle pressure and a downshift pressure responsive to the throttle pedal position to control the shift valves. The throttle valve unit 401 is located in bore 402 in the valve body and includes a throttle regulator valve 403 and a downshift valve 411. When the engine fuel feed control, such as a throttle pedal, is in the closed position, the valve unit 401 is in the closed position illustrated. Then the throttle valve 403, having lands a and b, is located in the bore 402 so that the upper land 403a blocks flow of oil from the main line 34%) via main line port 464 to the bore 402, but port 464 provides an annular passage around the land 4030 and always connects the main line 346 to the lockup cutoff valve unit 465. When the valve is in the closed position the land [2 is located below throttle port 436 and exhaust port 407 and the space between the lands connects the throttle line port 466 to exhaust port 487 to exhaust the throttle pressure in line 408. The throttle line 468 is also connected to the port 409 adjacent the closed end of the bore 402 so that the throttle pressure acts down on land a.

The downshift valve 411 has lands a and b of equal diameter spaced from one another and located in the bore 462 and a land 0 of larger diameter at the other end spaced from land b that enters bore 423. The throttle valve unit 401 is controlled by the accelerator pedal (not shown) which is connected by a linkage including lever 414 which engages the end face of land 0 to move tie downshift valve 411 into the bore 462 and increase the pressure exerted through spring 415 on the throttle regulator valve 433. Valves 403 and 411 have extensions projecting within the coil spring 415 which provide a locating device for the coil spring and a stop means to prevent the spring being compressed beyond its elastic limit. The throttle line 4431' is also connected to port 416 which is normally closed by the land a of valve 411 when the throttle pedal is in the closed or an intermediate position. When the valve 411 reaches the downshift position which may be at high throttle, full throttle or just eyond full throttle position, the space between the lands a and 12 connects throttle pressure line 403 via port 416 to port 417 which connects throttle pressure, now at a maximum but less than line pressure, to the downshift line 418. The port 417 is also connected through an orifice 419 to an exhaust port 421. The orifice is small so that when the regulated line pressure is open to line 418, the pressure is not materially reduced and downsaifts the shift valves. However, when the detent line 413 is closed by the land a of valve 411, the trapped oil will drain through orifice 419 to exhaust 421 to prevent oil locked in line 418 interfering with the action of the shift valves. At the same time or just before the throttle pressure line 468 is connected to the downshift line 418, the port 422 connected to throttle line 408, now at line pressure, is open to the space between lands 1) and c and the oil tends to flow into the large open end portion 423 of bore 402 and, substantially simultaneously, the large land c of downshift valve 411 enters bore 423 to provide a fluid detent action. It will thus be seen that further movement of the valve 411 requires an additional force to overcome the force of the pressure in throttle line 408 acting on the unbalanced area between the lands 1) and c of valve 411. Thus the operator will be required to exert an extra force on the throttle pedal to energize the downshift line 418 to effect a downshift. The shoulder 429 on land 0 limits movement of the valve 411. The throttle valve unit 4%)1 provides throttle pressure in line 468 directly proportional to the throttle pedal position and a downshift pressure in line 418 effective at a certain point of throttle movement such as high or full throttle or slightly beyond full throttle to effect a downshift.

Speed Governors The transmission control system employs two governor pressures, the front governor pressure, proportional to the speed of the splitter gear unit output or connecting shaft 33, and the rear governor pressure, proportional to the speed of the transmission output shaft 69 which is proportional to vehicle speed. The shaft 33 drives the front Pitot governor 51 (FIG. 1) to provide a governor pressure in line 220 proportional to the speed of shaft 33. The rear Pitot governor 86 has a trough 311 driven by the output shaft 69 and provides a pressure in line 320 proportional to the output shaft speed. These governor pressures and the above-described throttle pressure and downshift pressure are employed to control the automatic shift valves to provide automatic speed ratio changes.

9 Manual Valve The operator positions the manual valve unit 427, FIG. 6, to select one of the ranges, Reverse, R, Neutral, N, Drive, D, Fifth Gear Hold, 5, Intermediate, Int, or low, L0, in which the transmission may be automatically controlled. The oil in main line 340 flows through orifice 424 or the lockup cutoff valve unit 465 (FIG. 6), as explained below, depending on the position of the lockup cutoff valve unit, to the ratio change line 425 which is connected to the bore 426 of manual valve unit 427. The valve 428 is slidably mounted in the bore 426 and has land 428a at the top end and land 528b at the center and an aperture 431 at the other end to connect the valve to the manual control linkage. With the valve in the neutral position illustrated, the controlled main line 425 enters the bore 426 and is connected between lands a and b to drive signal line 435. Upward movement of the valve 428 to the reverse position R will connect line 425 to reverse line 310. Movement of the valve 428 downwardly to the drive range position D connects the controlled main line 425 via the space between the lands a and b to the drive range line 432 and drive signal line 435 which prevents disabling the splitter shift valve unit 4%. In fifth gear hold position (5) main line 346 remains connected to drive range line 432 but is disconnected from drive signal line 435 to permit high ratio line 210 to disable the splitter shift valve 4% to hold the transmission in fifth ratio as explained below in connection with the splitter shift valve unit 49%). Further movement of the valve 428 to the intermediate range position Int will similarly connect the control line 425 to both the drive range line 432 and the intermediate range line 433 and movement of the valve to the low position Lo will connect controlled line 425 to the drive range line 432, the intermediate range line 433 and the low range line 434. When the valve 428' is-in the neutral position, it will be seen that the reverse line 318 is connected to exhaust through the adjacent end opening 436 of the bore 426 to reverse exhaust valve 438, and the lines 432, 433 and 434 for the various drive ranges are connected to a free exhaust at the adjacent end opening 437 of the bore 426.

The reverse exhaust valve 435 maintains a very low pressure just to fill reverse clutch line 310 and motor 83 but insufficient to move the motor against the retraction springs. Leakage is replaced through reverse make-up line 439 and orifice 446 which connects the regulated line 349 with reverse line 319. The orifice 440 limits the flow to the approximate quantity to make up for leakage in the reverse clutch motor.

When the valve 428 is in the drive range position, the intermediate range line 433 and the low range line 434 are connected to exhaust 437 and, in the intermediate pt sition, low range line 434 is connected to exhaust 437. T36 valve 423 between the lands 428a and b has a series of annular grooves 441, one for each valve position, which cooperate with the spring-loaded ball detents 442 to resiliently hold the valve in the selected range positions.

Lockup Valve Unit The lockup valve unit 445 (FIG. 5) automatically controls the lockup clutch 16 and the converter pressure. The mainline 340 is connected through the check valve 333 to the lockup valve unit 445. The lockup valve 446 has an end land a, a central land 11 having the same diameter slidably mounted in a bore 447 in the valve body, and a land 0 adjacent the other end of smaller diameter which fits in a smaller diameter bore portion 448. The valve 446 has a stud'45l extending above land a which serves to limit the upward or opening movement of the valve 446 and locate spring 452 in the spring chamber 453. The spring 452 engages the end of chamber 453 and the valve to resiliently urge the valve 446 in a closing direction. The throttle pressure and forced downshift pressure are connected by the downshift line 418 to the spring chamber 453 to act on the free end of land 446a and close valve 446 to tend to disengage the lockup clutch. The front governor pressure in line 220 acts on the lower face of the lockup plug 455 located in an enlarged portion 456 of the bore 447 to move valve 446 toward open position. When the valve is in the closed position, illustrated in FIG. 5, the land b blocks the main line 340 and the governor controlled lockup feed line 395 is connected between the unbalanced lands 5 and c to the exhaust 457. Exhaust 45% provides a drain between valve 446 and plug 455 to prevent the accumulation of oil under pressure due to leakage. The secondary line 356 is connected between the lands a and b when the valve 446 is in the closed position to the converter inlet line 1%. Thus when the converter is functioning and full regulated main line pressure is supplied to the secondary line 356, this pressure is connected to the converter inlet line 100. Due to the normal flow of oil in line 160 through the converter and cooler 711, the pressure in converter inlet line is lower than main and secondary line pressure as controlled by the pressure control unit 341. However, if flow in line 1% is restricted for example, by cold oil in the cooler 711, the converter charging pressure could rise to main line pressure which is too high. The converter pressure regulator valve 462 limits the converter charging pressure in line at a value between normal converter charging pressure and main line pressure to prevent an excessive converter charging pressure.

The lockup valve 446 is controlled by spring 452 and the throttle pressure in line 408 acting via downshift line 418 to close the valve against the front governor pressure in line 223 acting to open the valve. When the governor pressure increases sufficiently due to the increase in the intermediate shaft speed to overcome the spring force and the throttle pressure, the valve 446 moves and land b uncovers the main line 340 and permits oil under pressure to flow between lands 46 6b and c to act on the unbalanced area of lands b and c to tend to hold the valve 446' open to prevent hunting and to provide a hysteresis loss so that a downshift will only occur at a lower speed. With valve 446 in the open position, the main line 344 is connected to the lockup clutch feed line 395 and to the lockup cutoff valve 465 which connects to the lockup clutch line 30 except during a shift as explained below. At this time the land 0 closes exhaust port 457.

If desired, the lockup valve 446 may be controlled by the spring 452 acting against the front governor pressure by disconnecting the downshift line 418 from the locklup valve unit 445 and connecting spring chamber 453 to exhaust.

Since the converter 4 is inoperative when the lockup clutch 16 is engaged, except during brief shift intervals, the lockup valve is used to reduce the converter pressure when valve 446 is opened to engage lockup clutch 16. When the lockup valve 446 is opened, the land b closes the converter inlet line 100, and stops the flow of the oil from the secondary line 356 to the converter inlet line 130. The pressure in the converter thus drops until it reaches a lower value maintained in the low pressure line 362 by the pressure control unit 341. The exhaust from the regulator valve unit 341 in exhaust 361 is maintained at a controlled low pressure by the relief valve 363 andfiows through check valve 461 and low pressure feed line 362 to the converter inlet line 100. Check valve 461 prevents flow from converter feed line 100 to relief valve 363. g

The lockup shift valve 445 will upshift in all forward and reverse ratios.

Lac/cup Cutoff Valve Unit The lockup cutofi valve unit 465 (FIG. 6) which disengages the lockup clutch 16 during each ratio change interval includes a valve 456 having lands a, b, and c located in a bore 467 of uniform diameter. With the valve in the normally open position, as illustrated, the controlled lockup feed line 395 and the lockup clutch line 99 are connected by the space between the lands a and b. The exhaust port 46:? for the lockup clutch line 90 is blocked by the land 466a. A spring 471 positioned in one end of bore 467 urges the valve 465 to this opened position. A pin 472 mounted on the valve body locates and limits the compression of this spring. Main line 345) is connected to the other end of bore 467 and bypass passage 4-76 of the ratio change line 425 is connected opposite land c. The main line oil is connected by line 340 to the bore 467 beneath the valve to act on the free end of land spaced from the end of the bore by stud 478. The oil normally flows through orifice 424 when cutoff valve 466 is in the normally open or tie cutoff position and through bypass 476, when vlvc 456 is further opened, to limit the pressure drop across orifice 424 to supply the ratio change line 425 which is connected to supply the manual valve unit 427 and splitter shift valve 490 (-FIG. 4) and to control the lockup cutoff valve 466. Line 425 is connected, to control valve 466, to the bore 467 through an orifice 4-81.

The lockup cutoff valve unit 465 in its normal position is open to permit flow from the lockup valve unit 445 and controlled lockup feed line 395 to the lockup clutch line 90 and clutch 16 due to the action of spring 471 and the balanced opposing pressures in main line 349 and ratio change line 425 on the end faces of valve 466. Whenever the oil flows through ratio change line 425 to effect a change in ratio by filling one of the ratio motors, oil flows from the main line 346 through the orifice 42-4 creating a pressure difference between the oil in the main line 343 acting on the end face of land 0 and the oil in ratio change line 425 which acts on the opposite end face of land 456a. The higher pressure in line 340 raises valve 466 against spring 471 and connects lockup clutch line 99 to exhaust 468 and blocks controlled feed line 395. An excessive difference in pressure between main line 349 and ratio change line 425 will raise valve 466 against spring 4-71 further to connect these lines momentarily via the bypass 476 to reduce the pressure differential. Thus the normal main line pressure applied to the ratio clutch motors is reduced during each shift inteival until the ratio motor is substantially filled and rapid flow stops. The point of engagement of the ratio clutch motor at which the pressure is increased and the lockup clutch engaged, is controlled by the force of spring 471. As the flow slows down, the pressure differential is reduced and at a certain low pressure differential spring 4-71 closes the valve '466. The flow of oil between line 425 to the spring chamber is restricted by orifice 431 to damp valve movement. When the lockup valve unit 445 opens, the lockup cutoff valve unit 465 will be in the normally open position illustrated to engage the lockup clutch 16 but will close during each ratio change interval to disengage the lockup clutch 79.

The rate of opening of the lockup cutoff valve 465 is controlled by a timer or accumulator 489 consisting of a piston 479 located in bore 4&2 and biased by spring 483 to the charging end 484- of bore 482. The abutment 485 limits piston movement and locates and limits compression of spring 483. When cutoff valve 455 is in the position shown, connecting the controlled lockup feed line 395 to lockup clutch line 90, main line pressure is supplied by line 90 and branch 90' to the spring chamber of bore 482 to one side of piston 479 and by line 425 and branch 425 to the charging end 484 of bore 482 to place the same pressure on opposite sides of piston 479 so spring 483 returns the accumulator. When cutoff valve 465 closes during a shift in ratio and line 90 is connected to exhaust 463 to disengage the lockup clutch, line 90' is also connected to exhaust 4&8 to condition accumulator 480 for charging. The accumulator spring provides a 12 force which permits the lower pressure in line 425 during a ratio change to charge the accumulator at a. slow rate limited by orifice 481. As long as the accumulator is being charged, the flow from main line 340 via orifice 424 to ratio supply line 425 provides sufficient pressure drop to hold lockup valve 466 in the closed position. Thus the accumulator holds cutofi valve 466 in the closed position disengaging the lockup clutch a predetermined time interval after the ratio shift is initiated to insure that the ratio shift is completed before the cutoff valve opens to re-engage the lockup clutch,

The accumulator may also be provided with a spring having a force which does not permit charging the accumulator at the normal low pressure in line 425 caused by full flow to the ratio motor, but which would begin accepting a charge as soon as the pressure began to rise and before the pressure in ratio line 425 equalled the pressure in main line 349. Thus the accumulator would start charging just as the ratio change was being completed and before the cutoff valve opened. Then the accumulator would be charged for a predetermined time interval delaying opening of the cutoff valve and reengagement of the lockup clutch for a predetermined period after the shift was completed.

Both arrangements provide torque converter operation for a limited time after the shift is completed to insure that the torque converter is operative and the lockup clutch disengaged until the shift is fully completed to provide a smooth nr ansistion between ratios.

The lockup cutoff valve 466 in the normal position connects limited feed line 511 to exhaust 573 and in the cutoff position connects lockup supply line 395 to the limited feed line 511 to supply make-up fluid via intermediate high shift valve 570 to exhaust valve 679.

Splitter Valve Unit The spliter valve unit 490 (FIG. 4) automatically shifts to control the ratio of splitter gear unit 27 by actuating the splitter high clutch 38 to provide direct drive or by actuating the splitter low ratio engaging device 36 to provide underdri-vc. The governor forces acting on the valve unit 498 are changed to shift the splitter unit at three different vehicle speeds depending on the ratio engaged in the three-speed unit 46, the first when in low ratio, the second when in intermediate ratio and the third when in high ratio in the three ratio unit 46 to provide six drive ratios.

The splitter shift valve 491, located in bore 492-494, has lands a, b, c and d with intermediate spaces of lesser diameter. Lands a and b having an equal larger diameter fit in upper large bore 492 while lands c and d having an equal smaller diameter fit the lower small diameter bore 4-94. With the splitter valve 491 in the low position illustrated in FIG. 4, the ratio change line 425, which is regulated by regulator unit 341 and controlled during each shift by lockup cutoff valve unit 465, is connected to the valve bore 492 between the lands a and b. The line 425 is thus connected between the lands a and I) to the splitter underdrive line 150. The controlled exhaust line 493 connected to the bore 492 opposite land a is blocked. The throttle pressure in line 408 enters the bore 492 via a port immediately adjacent the free end face of land a of valve 491 in the downshift position and acts on the valve 491 to hold it in this position. The downshift pressure in line 418 enters the bore 492 adjacent the end wall 4% and acts at all times upon the free end face of land a of valve 491 to move it to low position. The splitter control plug 497 having lands a and b is located in bores 498 and 499 respectively coaxially located with respect to bore 492. Land :1 of plug 4-97 closes the bore 499 at all times and at times acts on land a of valve 491. A spring 562 seated on piston 5&1 in stepped bore 500 biases plug 497 to engage the valve 491 to urge it to low position. The controlled lockup line 395 enters the bore 498 beneath land a of plug 497 to lift the plug 497 and eliminate the effect of spring 502 and the objectionable spring rate effect on the splitter shift valve 491 when the lockup valve 445 shifts to engage the lockup clutch. The shoulder 593 limits upward movement of the plug 497 and splitter valve 491. Thus the spring 502, unless made ineffective by lockup pressure from line 395, the throttle pressure from line 468 and the downshift pressure from line 418, tends to urge the splitter valve 491 down from high to low position.

In reverse, neutral and drive range positions of the manual valve unit 427, fiuid is supplied via the drive signal line 43510 the closed end of bore 5th) to move piston 501 down to the vented position. The movement is limited by the shoulders on the stepped piston 551 and bore Silt? to a small degree that does not materially change the spring force on the plug 497. Then movement of piston 591 to the vent position thus does not materially affect the operation of the splitter shift valve unit 490 in reverse and neutral. Since fluid is not supplied by signal line 4-35 in low, intermediate and fifth gear hold range, the piston 551 remains in the upper or closed position shown but is effective only in fifth gear hold when fluid is supplied by the high ratio line 210 via port 594 in piston 551 to the closed bores 498-559 to act on plug 497 to hold the splitter shift valve unit 4% in the downshift position. in drive range fluid supplied via line 435 moves piston 551 down aligning port 504 and exhaust 5195 to vent bores 49 8-5i36 to permit normal operation of valve unit 4%.

With the valve 491 in the low position shown, the direct drive clutch line 17% located between large bore 492 and small bore 494 is connected between the lands b and c to exhaust port 5%. The exhaust port 513 vents the space between the lands c and a.

With the valve in the upper or high position, the main line 425 is connected between lands b and c to the high ratio line 17f) and the low ratio line 156) is connected to controlled exhaust line 493.

Since the splitter valve 491 shifts the splitter gear unit 27 between low and high ratio when the threespeed gear unit is in each of the three ratios, low, intermediate and high, combinations of the two governor pressures, front governor pressure (line 229), and rear governor pressure (line 3211), provide three separate shift points. With valve 451 in low position illustrated in FIG. 4, the relay valve controlled line 517 may supply lockup pressure from line 3% to thebore 494 between land d of valve 491 and the front governor splitter plug 518 which is located in bore 494 and engages land a. A low intermediate valve controlled front governor line 521 is connected to the valve bore 494 at the partition 551 having an aperture smaller than bore 494 and between front governor plug 518 and rear governor plug 522. A rear governor splitter plug 522 is positioned in the large bore 523 located coaxially with respect to the bore 494. Plug 522 has a stern 524 having a diameter smaller than plug 518 extending through theaperture in wall 516 to engage the lower face of front governor plug 518. The intermediate high controlled rear governor pressure in line 525 enters the bore 523 between the partition 516 and the plug 522 to urge the plug 522 down away from valve 491. The rear governor pressure in line 320 enters the end of the bore 523 via orifive 527 to act on the end face of plug 522 to urge the plug 522 and valve 491 up to high drive position. The rear governor pressure in line 32%) acting on the lower face of plug 522 when the three ratio unit is in high and intermediate is opposed in intermediate ratio by the intermediate high controlled rear governor pressure in line 526 acting on the smaller upper face or rear governor plug 522 to provide a reduced governor force in intermediate ratio. The low intermediate controlled front governor pressure in line 521' acts in low range between the front governor plug 518 and the rear governor plug stern 524 to urge the valve 451 to direct drive position and hold stem 14 524 and plug 522 down. The intermediate high controlled lockup pressure in line 517 acts, when an upshift or downshift between low and intermediate range is initiated, between land d of valve 491 and front governor plug 518 to urge the valve 451 up toward direct drive position and hold plugs 518 and 522 down.

The rear governor line 320 between the orifice 527 and the splitter valve unit 491 has a branch 528 connected to the operating chamber of accumulator 529. The accumulator spring is sufficiently strong so the accumulator is not charged until after the third fourth ratio shift of the splitter shift valve. Thus, the accumulator does not affect upshifts. After the fourth fifth ratioupshift since rear governor pressure is high and since intermediate line 25th is exhausted governor pressure charges the accumulator. The accumulator is discharged on a downshift to intermediate ratio since intermediate ratio line 259 is connected by branch 526 to the spring chamber of the accumulator. The discharge of the accumulator holds the splitter shift valve in the upshift position to insure a 54 or 64 ratio shift except under unusual conditions.

These governor forces tending to move the valve 491 from low to high position are opposed by spring 502, until disabled by rear pump pressure, and throttle and downshift pressures tending to return the valve to low position. When valve 491 is in high position, the main line pressure acting via ratio change line 425 on the unbalanced area of lands 43112 and 0 provides the hysteresis action by tending to hold the valve in high position.

Low Intermediate Valve Unit The low intermediate shift valve unit 539 is. hydraulically controlled by manual valve unit 427 to shift the three-ratio unit between low and intermediate ratio and to condition the splitter valve unit 490 to shift at the first or second shift point. This unit 530 consists of a splitter relay valve 531 located in a large bore 532 and low intermediate shift valve 533 located in a smaller diameter bore 534;

The relay valve 531' has lands a, b, and c of equal diameter with intermediate spaced. portions of reduced diameter providing flow spaces. In the intermediate and drive range position shown in FIG. 4, spring 536, located at the end of bore 532, holds the valve 531 on a strut 537 fixed between the bore 532 and bore.534. The low range line 434 is connected between the bores 532 and 534, and the oil acts on the end of land 0 of valve 531 to raise it against the spring 536 to the low range position where land a abuts stop pin 538. With relay valve 531 in the drive or intermediate range position, as shown, the lockup supply line 395 is connected to the bore 532 between the lands b and c adjacent the land b. The relay valve controlled line 517 is exhausted between the. lands a andb. A free exhaust port 541 is connected to the bore 532 between the lands a and [1. Immediately above land a of valve 531, the branch throttle line 541 is connected to bore 532 to insure that this portion of. the bore is filled with fluid. The end portion of. the bore 532 is enlarged and provides a spring chamber 543 connected to exhaust passage 546 by a one-way check valve 547 and an orifice 548 extending to a point under the oil level in the sump to keep the chamber full of oil to cushion valve movement.

With relay valve 531 in the intermediate and high range position shown, the lockup line 395 is blocked between lands 5311) and 0, controlled line 517 is connected between lands 531a and b to exhaust 541 and spring chamber 543 is filled with oil. When the manual valve 427 is moved to low range, oil in line 434 at main line pressure moves relay valve 531 up againstthe lower throttle pressure supplied by line 542. The first increment of movement, while line 542 is open, is fast and connects lockup line 395 to controlled lockup .line 517. After land a closes line 542, the oil in the spring chamber, being retained by check valve 547, slows the valve 531 and only permits very slow movement due to slow leakage of oil past land 531a to exhaust 542. During this slow movement, the lockup pressure in line 517 prevents a downshift of splitter valve unit 490. When land 531a enters the spring chamber and permits communication with line 542, the valve 531 is substantially in low range position engaging stop 533, land c blocks lockup line 395 and controlled line 517 is connected to exhaust 541 permitting normal downshift of splitter valve unit 490.

When the manual valve unit 427 is shifted from low range, low range line 434 is exhausted, spring 5336 returns valve 531 and draws oil from the sump through exhaust port 546, orifice 548, and check valve 547 to replenish the oil in spring chamber 543. Though the return movement is faster, since orifice 548 permits a greater fiow than the clearance at land 531a, lockup pressure from line 395 is momentarily supplied to controlled line 517 to momentarily inhibit a downshift of the splitter valve unit 490 during the shift interval. When valve 531 reaches the intermediate and high range position shown, the lockup line 355 is again blocked and line 517 connected to exhaust 541 and line 542 fills the spring chamher.

The low intermediate shift valve 533 located in bore 534 has lands a, b, c and d of equal diameter and intermediate portions of reduced diameter to provide intermediate flow spaces. The land (I has a shoulder 551 which engages the valve body at the end of bore 534 and limits upward valve movement under the influence of main line pressure supplied by drive range line 432 via bore 552 through valve 533 to chamber 553 in the intermediate high position, shown in FIG. 4, preventing contact with strut 537 and valve 531. The spring 555 seated in bore 556 in the top of valve 533 engages strut 537 and valve 533 to urge the valve down in low range when pressure is supplied to the top by low range line 434 and to the bottom by drive range line 432 and in reverse when no pressure is supplied and drive and low range lines 432 and 434 are exhausted. A stop 554 in chamber 553 limits downward movement of valve 533 in the low position.

When the low intermediate shift valve 533 is in the intermediate high position shown, the low exhaust port 557 located between the lands 533a and b is connected through low pressure relief valve 558 to sump to maintain a low pressure in exhaust port 557 and the connected low ratio line 270. The low make-up line 560 having an orifice 562 connects the controlled main line 425 to the exhaust port 557 to supply fluid lost by leakage to keep the exhaust port 557 and connected low ratio line 270 and the low ratio motor filled at a pressure insufficient for engagement. The drive range supply line 432 supplies controlled and regulated main line pressure to the bore 534 between the lands b and c. The intermediate high supply line 559 is connected to the bore 534 between the lands b and c. An exhaust port 561 is located between the lands c and d. The controlled front governor line 521 is connected to bore 534 between lands c and d. The front governor line 220 is connected to bore 534 opposite land d.

With the low intermediate shift valve 533 in the intermediate and high range position illustrated in FIG. 4, the

drive range line 432 is connected between lands b and c to the intermediate high shift valve supply line 559 and via bore 552 to chamber 553. The low make-up line 560 connects the controlled main line 425 through orifice 562 to port 557 to replenish leakage. The low ratio line 270 is connected between lands a and b to the low pressure exhaust port 557 and low pressure relief valve 558 which maintains low pressure oil in low clutch line 270 to keep the low motor filled. The controlled front governor line 521 is connected between lands and d to orifice exhaust 561.

When pressure in the low range line 434 acts between land 0 on valve 531 and land a on valve 533, to separate the valves, the relay valve 531 moves up as explained above and the valve 533 is moved down to the low range position by spring 555 since the low range pressure on top balances the drive range pressure on the bottom. In low range position, the drive range line 432 is con nected between the lands a and b to the low ratio line 270 and low exhaust 557 is blocked by land a. The intermediate high supply line 559 is connected by the space between the lands b and c to exhaust 561. The front governor line 229 is connected between the lands c and d to the controlled front governor line 521 to provide front governor pressure on splitter plug 518 for a first to second ratio shift in low range when the three ratio unit 46 is in low.

In reverse, since pressure is not supplied to low range line 434 and drive range line 432, spring 555 moves valve 533 down to the low or reverse position. The low clutch line is exhausted to drive range line 432 which is exhausted at manual valve 427. The intermediate high supply line 559 is connected to exhaust 561. Front governor line 220 is connected to governor relay line 521 to actuate splitter shift valve 499 in reverse to provide two ratios.

Intermediate High Shift Valve Unit The intermediate high shift valve unit 570 (FIG. 3) automatically controls the intermediate high shift and one of the governor pressures acting on the splitter valve 490. The intermediate high shift valve 572 located in bore 571 has large diameter lands a and b located in a large bore portion 573 and small diameter lands 0, (l and e located in a small bore portion 574 and intermediate portions of smaller diameter between the lands. At the upper end of the bore 571, the wall 581 has a smaller diameter bore for the stem 582 of the intermediate high blocker plug 583 which has stepped leands a and b with the small land a adjacent the stem 582 fitting in the intermediate size coaxial bore 536 and a second land b at the end located in the large coaxial bore 587. Spring 591 engages the endWvall of bore 587 and the upper face of land b of plug 583 to urge the blocker plug 533 and shift valve 572 toward the intermediate position. A stud 592. fixed on the end wall of bore 537 limits upward movement, in the high position of valve unit 576. The intermediate range line 433 energized by manual valve unit 427 is connected to bore 587 near the end wall. At the shoulder between the bores 587 and 586, there is an exhaust port 594 to drain leakage oil. The rear governor line 325) is connected by port 593 to the bore 586 adjacent the wall 531 so that rear governor oil acts on the face of land a adjacent the stem 532 to move plug 583 up against spring 591. The downshift pressure supplied by the throttle valve unit 401 is connected by downshift line 418 to bore 573 adjacent wall 581 and acts to raise the stem 582 and plug 583 and to act on the end face of the land a of valve 572 to move the valve down toward intermediate position. The throttle pressure in line 463 enters bore 573 just above the land a of valve 572 and tends to move the valve 572 down toward intermediate position and to move the plug 583 away from the valve 572. On upshift of the valve 572 to the high position, the land a will close the port of throttle line 408.

With valve 572 in the intermediate position illustrated in FIG. 3 the intermediate ratio clutch is engaged, and the controlled intermediate exhaust line 601 is blocked by land a. The intermediate clutch line 250 is connected to the bore 573 between the lands a and b adjacent land a of the valve 572. The intermediate high supply line 559 is connected to the bore 573 between the lands a and b adjacent land b. The high clutch line 210 is connected to the bore 573 between the lands b and c adjacent land b. Exhaust port 602 is connected to the bore 571 between the lands b and c adjacent land 0. The rear overnor line 320 is connected to a port 603 which is blocked by the land c. The controlled rear governor line 526 is connected to the bore 574 between lands c and d adjacent the land c. An exhaust port 607 is connected to the bore 574 between lands and d adjacent land d. The limited feed line 511 is blocked by the land d. The intermediate exhaust feed line 608 is connected to the bore 574 between lands d and e adjacent land a. An exhaust port 611 is located between lands d and e adjacent land e. An exhaust port 612 is located adjacent the end face of the land e of valve 572.

At the end of shift valve 572, bore 571 has a large portion 614 for the intermediate high plug 616 which engages land 2 of valve 572 and stem 621. A port 617 in bore 614 adjacent the end wall 618 is connected to the rear governor line 320 so that the rear governor pressure acts on the lower face of plug 616 to urge the valve 572 up to high position. A transfer stem 621 extends through an aperture in wall 618 to a larger bore 622 located coaxially with respect to the main bore 571. The intermediate high accelerator plug 624 is located in bore 622 and acts through the stem 621 and the governor plug 616 on valve 572 to raise it toward high position. The controlled intermediate exhaust in line 601 is connected by port 626 to the lower end of bore 622 to act on the free end face of plug 624 to tend to move the valve assembly toward high position. Bore 622 between plug 624 and wall 618 is drained by exhaust 627.

The intermediate high shift valve 572 is urged to the intermediate position illustrated in FIG. 3 by the spring 591 acting through the intermediate high blocker plus 583 unless rear governor pressure in line 420 lifts the plug to disable the spring, by the pressure in intermediate range line 433 on plug 583 which is effective in intermediate and low ranges regardless of rear governor pressure, and by downshift pressure in line 418 and throttle pressure in line 408 acting on end face of land 572a. If one or more or these downshift forces overcome the upshift forces, valve 572 is in the intermediate position and the intermediate high supply line 559 is connected between lands a and b to intermediate clutch line 250. The high clutch line 210 is connected between lands b and c to exhaust 602. Rear governor line 320 is blocked by land 0 and controlled rear governor line 526 is connected between lands 0 and d to exhaust 607. The limited feed line 511 is blocked by land a. and the intermediate exhaust feed line 608 is vented between lands d and e to exhaust 611.

In high range when intermediate range line 433 is exhausted, the valve 572 is conditioned by governor line 320 supplying oil under pressure to port 593 to raise blocker plug 583 and spring 591 out of engagement with valve 572 to provide a rateless valve. The rear governor pressure at port 617 then acts on the outer end of governor plug 616 against throttle pressure acting on land a to upshift valve 572. When valve 572 is upshifted to high position, the intermediate clutch line 250 is connected between lands a and b to the controlled intermediate exhaust line 601 which is also connected below the accelerator plug 624 to urge valve 572 to high position during the controlled intermediate exhaust period to provide hysteresis before the high clutch pressure has built up sufficiently to provide hysteresis on the unbalanced area of the shift valve. The intermediate high supply line 559 is connected between unbalanced lands b and 0 providing hysteresis to high clutch line 210 to engage the high clutch. Rear governor line 320 is connected via port 603 between lands 0 and d to the controlled rear governor line 526. The limited feed line 511 is connected between lands d and e to the intermediate exhaust feed line 608 and exhausts 607 and 611 are bloclged by lands d and e.

Downshift Timing Valve Referring to the top of FIG. 4, the downshift timing valve unit 630, which controls the engagement of the intermediate clutch has a valve member 631 with lands a and b of equal diameter connected by an intermediate portion of reduced diameter to provide a flow space and an end land c of smaller diameter located in a stepped bore 632. Spring 635 located in the vented end of bore 632 normally holds valve 631 in the closed position shown. Throttle oil in line 408 is connected to the bore 632 to act on the end face of land 12 and low clutch oil in line 270 is connected through an orifice to bore 632 to act on the end face of land c to open the valve 631. The valve 631 normally closed by spring 635 and opened only by both low clutch pressure and throttle pressure between one-half and Wide open throttle. The portion of the intermediate clutch line 250 from the intermediate shift valve unit 570 is connected to the port 633 and the other portion of the intermediate clutch line 250 leading to the clutch motor 62 is connected to port 634. With the valve 631 in the open position, ports 633 and 634 are connected between lands a and b to freely connect the two portions of line 250. With the valve member 631 in the closed position shown, the land 0 engages the end of the bore to limit movement, and land a will block port 633 to cause the oil to flow through the orifice 636 connecting the two portions of line 250 to provide a slow feed for the intermediate clutch motor.

The valve 631 will be in open position when the oil in the low clutch line 270 applies low ratio clutch and the throttle is open, preferably one-half or more, there will be free flow through the valve 631 and line 250 permitting a quick application of the intermediate clutch on a high throttle shift from low. When either the low clutch line is exhausted or throttle pressure is low, preferably below half throttle, the valve is closed to block port 633, the oil flows through the restricting orifice 636 in line 250 to effect a slow application of the intermediate clutch. Thus on a low throttle upshift from low to intermediate, and on all downshifts from high to intermediate, the intermediate clutch is slowly applied through restricting orifice 636.

Trimmer Valve Unit 640 The trimmer valve unit 64-0 regulates the pressure in the ratio change line 425 from an initial low value to a final value equal to main line pressure at gradually increasing values modulated by throttle pressure during the engagement of all of the ratio engaging devices under all torques and may thereafter rapidly increase the pressure to main line pressure. This unit does not regulate the pressure supplied to the lockup clutch by line 90. The trimmer unit has a trimmer valve 641 and a trimmer plug 644 located in a bore 642. A spring assembly 643, consisting of two spring elements 643a and 643b with an intervening cup 6430 permits in effect a longer spring with a more constant rate in the limited space between the regulator valve assembly 645 fixed at one end of the bore 642 and the plug 644 biases the plug and trimmer valve to the other end. The cup 643a limits movement of the plug toward the one end of the bore and excessive compression of the springs 643a and 643b. The valve member 641 has a central cavity 646 in which a spring 647 is located to provide a small separating force between the plug 644 and valve 641.

The regulator valve assembly 645 is fixed in bore 642 by pin 725 fitting a groove in valve body 726. The valve body 726 has a bore 727 receiving the piston 728. The bore 727 is closed at the outer end by the piston and has a wall 729 at the other end having a port 731. A spring 732 between the wall 729 and piston 728 biases the piston to the outer end into engagement with the end wall of bore 642. A spring 733 biases regulator valve ball 734 to close port 731. The lockup clutch line is connected by port 735 to the bore 727 between the 'piston 72S and wall 729. The throttle line 408 is connected to the end of bore 642 to act on piston 728. The lockup supply line 395 is connected by orifice 736 to the trimmer valve bore 642 between the regulator valve assembly 645 and the trimmer plug 644 to provide a biasing pres- 19 sure in the spring chamber to assist the springs, which pressure is regulated by regulator valve ball 734 at a pres sure variable in accordance with throttle pressure when line 90 is connected to exhaust. When lines 90 and 395 are supplied, main line pressure in the spring chamber disables the trimmer valve 640.

With the valve in the normal position shown in FIG. 7 when the pressure in the ratio change line 425 is reduced due to the filling of a ratio change motor, the flow through the orifice 424 at the lockup clutch cutoff valve 465, FIG. 6, actuates the lockup cutoff valve to cut off the supply of pressure from the lockup shift valve 445 via line 395 to the lockup clutch line 90.

When line 90 is exhausted to disengage the lockup clutch 16, the regulator valve ball 734 of valve assembly 645 will function to reduce main line pressure in the bore at spring 643 to a low throttle modulated biasing pressure to condition the trimmer unit for operation. The reduced pressure in line 425 is connected to the other end of the bore 642 and acts to move the valve 641 and plug 644 as a unit against the biasing force of spring 643 and the biasing pressure just enough to permit the escape of fluid via exhaust 648 to regulate the pressure at an initial low value. The initial low pressure value increases with the throttle modulated biasing pressure and thus increases with increasing torque demand. At the same time the fluid from line 425 passes through the orifice 649 into the substantially filled chamber 646 between the valve 641 and plug 644 and increases the pressure in the chamber to a value almost equal to the pressure in line 425 to permit the spring 647 to begin to separate the valve and plug and increase the effective biasing force of spring 643. The biasing force of the spring 643 is increased since the separation of the valve and plug increases the length of the unit so that the spring operates progressively in a more compressed condition providing an increasing biasing force. The size of the orifice 649 will determine the rate of separation of the valve and plug and thus the rate of increase of the pressure in the ratio engaging devices supplied by the line 425. As the pressure in line 425 continues to rise due to the separation of the valve 641 and plug 644, the plug will engage the cup 6430 which abuts valve assembly 645 at substantially the maximum pressure regulated by valve unit 640. Then the pressure in chamber 646 plus the force of spring 647 will move the valve 641 to close the exhaust. The spring 647 provides a small force so that the valve 641 closes when the plug abuts the stop and the pressure in the chamber 646 reaches a value slightly below the lowest regulated pressure in line 425. This value is selected at a value lower than the lowest main line pressure but sutficient to fully engage the ratio engaging devices at any torque encountered during engagement on the gradual portion of the pressure rise curve. Then the pressure in line 425 quickly rises to main line pressure to provide the safety factor to maintain engagement at any torque.

It will be appreciated that as long as the pressure in line 425 is being regulated and thus exhausted at exhaust 648 that there will be a pressure drop from the orifice 424 holding the lockup cutoff valve unit 465 in closed position. As soon as valve 641 closes, the ratio engaging device having been filled and engaged during the gradual pressure rise, the pressure will equalize in lines 340 and 425 permitting the valve unit 465 to open to reengage the lockup clutch.

When the valve 641 closes, the ratio engaging motor having been filled, flow in line 425 ceases and thus the lockup cutoff valve 465 opens to supply fluid from line 395 to line 90 to engage the lockup clutch. When this occurs, the line 90, also being connected by port 735 to the bore 727, closes regulator valve 734 so that pressure supplied by line 395 to the valve bore 642 at spring 643 cannot escape and balances the pressure from line 425 at the right end of the bore and the spring 643 moves the plug 644 against the valve element 641 ejecting the fluid between the plug and valve via orifice 649,

It may also be desirable for some ratios requiring fast engagement to disable the trimmer valve unit 640. This is done, for example, in connection with the splitter high shift by connecting the splitter high line through check valve 639 to bore 642 between the valve 641 and plug 644 to disable the trimmer valve unit 640. The check valve 639 prevents flow from chamber 646 during normal operation of the trimmer valve unit during engagement of other ratios. The slots 638 insure that line 170 is, when the valve 641 is in the closed position, open to chamber 646.

Exhaust Valve Units The splitter low exhaust valve unit 650 (FIG. 7) provides overlap in the splitter gear upshift and consists of a splitter low exhaust valve 651 having a land a of large diameter located in a large bore portion 652, a small land b located in the small diameter bore portion 653 and a smaller intermediate portion providing a flow space. The spring 654 is located in the end of bore 652 and the throttle line 408 is connected to the end of bore 652 so that both the spring 654 and the throttle pressure always urge the valve down toward the exhaust pressure increasing position. With the valve in the neutral or balanced position shown, the exhaust port 657 is just closed by the land a. The exhaust from the splitter low servo, via clutch line 150, splitter low valve unit 490, and splitter low exhaust line 493 is connected to orifice exhaust 655 and to the valve bore between the large and small bores 652 and 653 and enters the space between the lands a and b of valve 651 to act upon the unbalanced area of land a to oppose the force of the spring 654 and throttle pressure. The orifice exhaust 655 permits release of splitter low even if the valve 651 sticks at a rate about equal or slightly less than the minimum rate of exhaust provided by valve 651. The splitter low exhaust plug 661 is positioned in large bore 662 coaxially located at the end of bore 653. The remote end of the closed bore 662 is connected to the direct drive clutch line 170 so that the oil in the direct drive clutch servo urges the shift valve upwardly with the exhaust from splitter low clutch line 493 against the spring and throttle pressure toward the pressure decreasing position. The vent port 663 located between the bores 653 and 662 prevents fluid acting on the adjacent faces of valve 651 and plug 661.

The low exhaust valve 651 will remain in the balanced position shown when the forces acting upwardly, the splitter low exhaust acting on the unbalanced area and the direct drive line 170 acting on plug 661, balances the forces acting downwardly, the spring and throttle pressure on land 6510. An increase in the forces acting upwardly or a decrease in the forces acting downwardly will move the valve 651 up to open exhaust port 657 and decrease the pressure in splitter low exhaust line 493 and clutch line 170. Under constant throttle conditions for a brief period after the splitter valve unit 490 shifts from low to high drive, the pressure in the splitter low clutch line 170 and splitter low exhaust line 493 is maintained at a reduced value regulated by the throttle pressure line 408 and spring 654. Then as the splitter high servo fills and the pressure in the splitter high clutch line 170 builds up, it acts on plug 661 of low exhaust valve 651 to connect line 493 to exhaust 657 to reduce the pressure. An increase in throttle pressure will increase the splitter low controlled exhaust pressure.

This valve provides overlap on a low to high shift of the splitter gear by holding splitter low pressure at a reduced or partial value until splitter high pressure increases to engage the splitter high clutch. With increasing throttle the overlap is increased since a higher splitter high pressure is required to exhaust the splitter low clutch.

The intermediate exhaust valve unit 670, which controls the exhaust from the intermediate clutch of the three ratio unit, consists of a valve 671 having lands a and b of equal diameter located in bore 673.

Spring 674 which abuts against the end of bore 673 and valve 671 and the throttle pressure connected by line 408 to bore 672 both act on the valve 671 to urge the valve down to the pressure increasing position. The spring 674 fits in bore 676 in valve 671 so that when valve 671 abuts the end of the bore the spring is not crushed.

With valve 671 in the neutral position as illustrated in FIG. 7, the exhaust port 677 is blocked by land a. The controlled intermediate exhaust pressure in line 601, which is regulated by regulator valve 601a (located near intermediate high valve 570) at a low pressure substantially lower than the pressure required to initially engage intermediate ratio and preferably just above the low pressure value required to hold intermediate ratio engaged, is connected to the exhaust valve unit 670 between lands a and b of valve 671 and to orifice exhaust 675. Orifice exhaust 675 permits disengagement of intermediate ratio if valve 671 sticks. The intermediate exhaust feed line 698 which is supplied through the intermediate shift valve 571) from the limited feed line 511 is connected to bore 673 between lands a and b. The high clutch servo oil in line 210 connected to the end of bore 673 acts upon the end face of land b to raise the valve toward the open or pressure decreasing position against the spring 674 and throttle pressure acting down to increase the pressure.

The intermediate exhaust valve unit 670 controls the overlap in the intermediate to high upshift by maintaining the exhaust from the intermediate clutch line 251) and line 661 at a high pressure until high clutch pressure overcomes the throttle modulated biasing force. Increasing throttle pressure in line 408 will increase overlap requiring a higher high clutch pressure to exhaust the intermediate clutch up to a predetermined throttle pressure limited by regulator valve 682 and thereafter provide constant overlap. Grifice 682a limits flow through regulator valve 682. Since the pressure in line 691 holding intermediate ratio engaged is just sufficient for engagement when the high clutch pressure is suflicient to initially engage the high clutch and shifts the exhaust valve 671 to dump intermediate pressure in line 601, the interme diate clutch will be substantially instantly disengaged.

Hydrodynamic Brake and Converter Supply Control Valve Unit The brake control valve unit 690 which controls the action of the hydrodynamic brake, illustrated in FIG. 7, consists of a valve 691 having lands a, b, c and d of equal diameter separated by portions of smaller diameter to provide flow spaces in bore 692. The spring 693, seated in the end of the bore vented by exhaust 696, engages the end face of land a which has a stud 694 which positions the spring and provides a stop to limit movement of the valve 691. The spring chamber portion of bore 692 has an exhaust port 696. At the other end of bore 692 there is a wall 698 apertured to slidably receive the operating stem 699 which is connected by a suitable linkage to the brake operating mechanism.

With the valve 691 in the brake-off position shown, the brake branch of the secondary line 356 which supplies oil to the brake from the pressure control unit 341 when the brake is on, is connected between lands a and b and blocked by check valve 695 in branch 697 of free cooler outlet line 714 which is connected to the same port between lands a and b as line 356. The branch 700 of the free cooler outlet line 714 and the restricted cooler outlet line 713 are connected to opposite ports and both are blocked by land a. The brake inlet line 180 is connected to the space between the lands b and c adjacent land b and the exhaust port 701 is located between the lands b and c and adjacent land c. The cooler inlet line 703 is connected to the bore 692 at a point blocked by the land 0. Brake outlet line 181 is connected to the space between the lands and d adjacent land 0 and vent 764- is connected between the lands 0 and d adjacent land a.

When the brake is'applied the valve691 is-rnoved into the valve bore 692 compressing spring 693 to the brake on position. This movement uncovers the secondary line 356 and free cooler outlet branch 697 gradually due to the tapered shoulder 706 of land b and provides a gradually increasing flow from these lines between lands b and c to the brake inlet line 1 80. If the cooler Ollllllt flow and pressure via line 714 is insufficient to add to the flow from line 356, the check valve 695 will close preventing back flow. At the same time, the brake outlet line 181 is connected between lands 0 and d to cooler feed line 703 and exhaust ports 701 and 704 are closed. The degree of movement of valve 691 regulates the volume of oil supplied in line 356 to the brake and thus controls the braking effort of the brake. Increasing flow of oil increases the quantity of oil in the brake chamber and the braking effort. Increased torque absorption of the brake increases the centrifugal pumping effect of the brake and brake outlet pressure which provides auto-circulation of brake fluid during braking.

The converter outlet line 101 (FIG. 1) is connected through one-way check valve 712 and cooler inlet line 703 to cooler 711. Check valve 712 prevents brake outlet oil flowing to the converter. The cooler outlet is connected to the free cooler outlet line 714 and the restricted cooler outlet line 713 having restriction 710 between the cooler and the lubrication supply branch 709. The restricted cooler outlet branch 799 is connected to the lubricating line 716 and to front Pitot governor feed 715. The pressure in the lubrication line 716 is regulated by the pressure relief valve 718 and the excess oil is by-passed via line 719 to the sump.

In the brake off position of brake valve 690, brake inlet line and outlet line 181 are connected to exhausts 701 and 764 to disengage the brake. Cooler feed line 703 is blocked by land 0 so converter outlet flow in line 101 must go through the cooler 711. The free cooler outlet line 714 is connected by branch 697, check valve 695, between lands a and b, line 356, regulator valve 341, lockup valve 445 and converter inlet to supply the converter with auto-circulated fluid. Land a of valve 691 blocks the restricted cooler outlet 713 and branch 700 of free cooler outlet 714.

Hydraulic Controls The manual control unit 427 is employed by the operator to select one of four automatic ranges, low, intermediate, fifth gear hold and drive ranges, reverse or neutral. In low range, where the three ratio unit 46 is in low, either first or second ratio is automatically provided, depending on whether the splitter gear unit 27 is automatically positioned in splitter low or high by the governor and throttle actuated splitter shift valve unit 496. When the manual selector valve is positioned in the intermediate range, the three speed unit 46 is in intermediate and either third or fourth ratio is automatically provided by a second shift point of the splitter shift valve unit 490 which shifts again under the influence of a different governor control and throttle control to provide either splitter low or high drive. In the drive range position of the manual valve, the automatic control provides third and fourth ratios previously available in intermediate range and, in addition, fifth and sixth ratios which are obtained by an automatic shift of the three ratio unit 46 from intermediate to high and a simultaneous downshift of the splitter valve and a third shift of the splitter shift valve from splitter low to high at a higher speed under the influence of another governor and the throttle pressure. Fifth gear hold range is the same as drive range except that the splitter shift valve is held in low when the rear unit is in high to prevent an upshift to sixth ratio, so only third, fourth and fifth ratios are provided. Reverse range provides reverse in the three speed unit and either splitter high or splitter low for two reverse ratios R1 and R2.

23 In the table below, X shows the ratios available in each range and the gear ratio of both the splitter and three ratio unit that is engaged (the others being disengaged) to provide the six transmission ratios. The approximate numerical value of each ratio in converter and lockup drive is also shown.

24 558 at exhaust 557. The intermediate ratio line 250 is connected to exhaust through intermediate high shift valve unit 570, line 559, low intermediate shift valve unit 530, line 432 and manual valve unit 427 to exhaust 437. High ratio line 210 is connected at intermediate high shift unit 570 (FIG. 3) to exhaust 602. The splitter Splitter Gear 3 Speed Unit Gear Lock- Neu- Lo Int 5th Drivo Ratio Ratio up tral Rge Rge Rge Rge Conv. Under Direct Lo I H R Drive Drive When the vehicle starts from a standing start, the drive is transmitted through the torque converter which provides additional torque multiplication until a certain speed, preferably the speed at which the converter acts as a fluid coupling, and is reached, while the transmission is in first ratio. At this speed the lockup valve unit 445 (FIG. 5) moves under the influence of vehicle speed and throttle position to engage the lockup clutch 16 to provide a direct drive bypassing the torque converter. The lockup clutch is also disengaged by the lockup cutoff valve unit 465 each time a change in the gear ratio is made in the six ratio unit so the fluid drive of the converter smooths the gear ratio change.

Neutral When the vehicle is at rest and the engine is started with the manual valve unit 427 in neutral, the engine drives the converter impeller housing 2 which is connected to drive the front pump 1%. Front pump 106 (FIG. 7) supplies oil under pressure via front pump line 327 to check valve 333 and main line 340. The ball check valve 336 prevents oil exhausting through rear pump line 329 and rear pump 321 which is now inactive. Main line (340) oil at a pressure regulated by regulator valve 341 is blocked at lockup valve unit 445 by land 446b and flows to throttle valve unit 401 (FIG. 6) to provide throttle pressure in line 408 if the throttle is advanced, and is connected at all times around the throttle valve 403 by the annular passage 404 to the lockup cutoff valve unit 465. Due to the initial filling of some ratio clutch motors, there is a pressure drop between main line 340 across the orifice 424 to the ratio change line 425, and the lockup cutoff valve 466 is momentarily raised supplying oil via bypass 476 until the flow ceases and the pressure is equalized in these lines. The line 425 conveys oil at main line pressure to the manual valve unit 427 which, in the neutral position illustrated, blocks the line 425 between lands a and b of valve 428 preventing engagement of any ratio in the three speed unit 46 and to the splitter valve unit 490 which, in the initial position shown in FIG. 4, connects line 4-25 between lands 491a and b to the splitter low line 150 to engage the splitter low device to place the splitter unit in low. The transmission gearing, remains in neutral since the three ratio unit is not engaged in any gear ratio.

When the selector valve 427 is in neutral, the low and reverse lines 270 and 310 (FIG. 4) are maintained full of oil so that a rapid shift can be made between these gears for rocking the vehicle. Oil is supplied to reverse line 310 by orificed reverse make-up line 439 and limited to a low pressure only sufficient to fill but not actuate the reverse motor by the reverse relief valve 438 in exhaust 436. The low ratio line 270 and low motor is similarly filled with oil via orifice 562 and low make-up line 560 (FIG. 4) which is limited to a pressure insufficient to engage the low clutch by the low relief valve high ratio line 170 is connected by the splitter shift valve 491 (FIG. 4) between the lands b and c to the exhaust 506.

At this time the pressure in main line 340 is regulated solely by the main line pressure acting on the unbalanced area of lands b and c and the opposing action of spring 367, on valve 343 of pressure control unit 341 (FIG. 5) to provide a constant pressure.

When the pressure in main line 340 reaches the level controlled by the spring 367, valve 343 is raised until the land b permits the flow of oil to the secondary line 356. When the manual valve unit 427 is in neutral or any drive position and the lockup valve 445 in disengaged position, the secondary line 356 is connected between lands a and b of lockup valve member 446 to quickly fill the converter. The check valve 461 prevents flow from converter inlet line through the low pressure line 362. Relief valve 462 in line 10'.) will be active in neutral, if the restriction in the converter and cooler circuit tends to raise the pressure in line 100 to an excessive value.

The oil will flow out of the converter through the converter outlet line 101, check valve 712, cooler 711 and restricted cooler outlet line 713, to the front Pitot feed 715 and the lubricating system 716 and to free cooler outlet line 714 to brake valve 690. The pressure in the converter is regulated by the regulating valve unit 341 which normally regulates the same pressure in the secondary line 356 and the main line 340. When there is an excess of oil for these lines, the regulator valve 343 moves up toward the exhaust position and vents the front pump line 327 directly past the land a to the low pressure exhaust port 361. At this time, since there is full regulated line pressure in converter inlet line 100, the oil in port 361 cannot flow through line 362 and will exhaust through the low pressure relief valve 363.

This converter supply system with the brake valve 690 in the brake off position provides a converter auto-circulation system. The left portion of line 356 delivers oil via lockup valve 445 and line 100 to the converter. The converter outlet passes through line 101, cooler 711, brake valve 690 in the brake off position, the right portion of line 356 and the left portion of line 356 in sequence forming a loop circuit for the converter autocirculation system. The fluid is circulated by the pumping action of the converter which circulates fluid from inlet 100 at the low pressure zone or the pump inlet to the outlet 101 at the high pressure zone or the turbine outlet. In the brake on position of valve 690, right line 356 supplies fluid to the brake.

When the converter 4 is filled and the splitter low clutch 35 is engaged in neutral, the converter and splitter low drives the intermediate shaft 33 and the front governor 51 to provide a low front governor pressure in line 220. The front governor line 226 is connected to the lockup valve unit 445 where it is opposed, when starting the vehicle, by greater spring and throttle forces to prevent lockup in neutral. Though racing the engine could upshift valve unit 445 to engage the lockup clutch, it would be disengaged by the lockup cutoff valve unit 46 5 when a ratio in the three ratio unit 46 is engaged to start the vehicle and then load would reduce the engine speed to downshift the lockup shift valve unit 445. The front governor line 229 is also blocked by land d of the low intermediate shift valve 533 and thus cannot act on splitter shift valve 491. The splitter shift valve 491 and the intermediate high shift valve 572 are held by their springs in the downshift position and the relay valve 531 is held by its spring in the upshift position. The low intermediate shift valve 533 is held in the downshift or low position by its spring. Thus the vehicle always starts moving with converter and low splitter gear drive.

Low Range When the vehicle is standing with the engine idling, and the manual valve unit 427 is moved to the low range position Lo, the ratio change line 425 is connected between the lands a and b to the drive range line 432, the intermediate range line 433 and the low range line 434 and remains connected by splitter shift valve unit 490 (FIG. 4) to engage splitter low. Line 434 is connected to the low intermediate shift valve unit 530 between the splitter relay valve 531 and the low intermediate shift valve 533 to move these valves apart to the low range position. The splitter relay valve is moved against spring 536 to the low position. The low intermediate shift valve 533 with low range line 434 pressure on top on drive range line 432 pressure on the bottom on balanced arcs is moved down to the low position by spring 555. Since there is no lockup pressure in line 395 because the vehicle is standing or not moving fast enough for lockup, the relay valve 531 does not connect the lockup pressure by line 517 to upshift the splitter valve. The intermediate range oil in line 433 is connected to spring chamber or large bore 587 of the intermediate high shift valve unit 570 (FIG. 3) and acts on intermediate high blocker plug 583 to hold the intermediate high shift valve 572 in the intermediate position. The drive range line 432 is connected by the space between the lands a and b of the low intermediate shift valve 533 when in the low range position to the low ratio line 270 and is blocked from the intermediate high supply line 559 to prevent engagement of the intermediate ratio line 250 and high ratio line 210. The movement of the manual valve 427 to low range places the transmission in first ratio by supplying oil to raise the pressure in low ratio line 270 and engaging device 72 to place the three ratio unit in low ratio. The splitter gear unit having been in splitter low when the engine was started with the selector valve unit in neutral remains in splitter low. The transmission is in first ratio but with the engine at idling speed there is sufiicient slip in the torque converter so that no drive is transmitted. As the driver advances the throttle and increases the engine speed, torque is transmitted and multiplied in the converter and the vehicle starts to move. The maximum pressure in the converter chamber is controlled by valve 462 when the lockup clutch is disengaged and drive is transmitted through the converter. At the same time, the throttle linkage connected through lever 414 (FIG. 6) acts on the throttle valve unit 401 to move the downshift valve 411 which, through the springs 415, moves the throttle valve 403. As the throttle is advanced, the land a of valve 403 uncovers the regulated line 340 so that oil flows between lands a and b to throttle line 498 which is also connected to the end of valve 403 to act on an unbalanced area of the valve and provide increased throttle pressure in line 408 with increasing throttle pedal position.

When the converter reaches the coupling stage, front governor pressure in line 220, acting on lockup plug 455, moves the valve 446 (FIG. 5) up at about four miles per hour to lockup position against spring 452 and throttle pressure in downshift line 418 acting on land 'a. Throttle pressure from line 408 is present in downshift line 418 except in sixth ratio, since these lines are interconnected at the splitter shift valve unit 490 and the intermediate high shift valve unit 570 when these valve units are in the downshift position. When the valve 446 is moved to lockup position, the lockup feed line 395 is disconnected from exhaust 457 and connected to main line 340 which acts on the unbalanced area of lands b and c to provide hysteresis so that the lockup clutch is disengaged at a lower speed. Lockup feed line 395 is connected (FIG. 6) by lockup cutoff valve 466 in the normal position shown to the lockup clutch line 9i) to engage the lockup clutch 16. The lockup feed line 395 conveys oil to the pressure control unit 341 at the lower face of land b of knockdown plug 349 to reduce the pressure in main line 340 and secondary line 356. The main line pressure is always increased with increasing throttle pressure in line 408 and brake pressure in line 181 as explained in the above description of the pressure control unit 341.

When the lockup valve unit 445 is in lockup position directing engagement of the lockup clutch, the secondary line 356 is blocked by land b of valve 446 and cannot supply the converter inlet line 100. As the pressure in the converter decreases due to flow to the cooler, the low pressure'exhaust from the pressure control unit 341 at port 361 will flow through the line 362 and check valve 461 to the converter inlet line and provide a low pressure feed at the pressure regulated by the relief valve 363.

As the vehicle accelerates, the front Pitot pressure 220, and the rear governor pressure 320, increases in proportion with the rear wheel speed.

Splitter shift valve unit 490 in low range, is held in low by spring 592 connecting the ratio change line 425 to the splitter low ratio line until lockup and then conditioned for an automatic shift by lockup oil supplied by line 395 to plug 495 to disable the spring on lockup and then is automatically shifted by throttle and governor pressures to connect the splitter low ratio line 159 to the splitter low exhaust line 493 and connect the ratio change line 425 to the splitter high ratio line 170.

On lockup, lockup pressure in line 395 acts on the lower face of plug 497 to lift spring 502 to free the valve 491 so that rateless valve control is obtained. The throttle pressure in line 408 is connected to the end of the bore 492, which is closed by plug 497, and urges valve 491 toward the splitter low position. Though throttle pressure line 468 is connected in bore 432 to downshift line 418 which is exhausted through orifice 419 (FIG. 6), the small orifice 419 does not reduce this pressure enough to affect the operation. The governor pressure proportional to speed acts to move the splitter valve 491 up to splitter high position. The low intermediate valve 533 now in low range position, connects front governor line 2241 to relay controlled front governor line 521 and disconnects it from exhaust 561. Front governor line 521 is connected to splitter valve unit 490 to act on the lower face of front governor plug 518. The lower pressure rear governor oil in line 320, though acting on the lower face of the rear governor plug 522 is ineffective, since it is not high enough to overcome front governor pressure acting down on the plug. The intermediate high controlled rear governor line 526 is connected to exhaust at the intermediate high valve unit 570. The relay valve 531 in the low range position is raised and blocks lockup line 395 and connects controlled rear pump line 517 to exhaust 541. The splitter valve 491 is thus controlled by the throttle pressure which tends to move the valve toward splitter low position and the front governor pressure acting via relay controlled line 521 to move the valve up to the splitter high position at about 12 miles per hour depending on throtile position. The splitter shift valve 491 which in first ratio connects ratio change line 425 to splitter low ratio line 150 and splitter high ratio line to exhaust 506, shifts up for second ratio to connect ratio change line 425 to split- 

1. IN A TRANSMISSION; A DRIVE TRAIN INCLUDING A TORQUE CONVERTER HAVING AN INPUT MEMBER AND AN OUTPUT MEMBER AND A LOCKUP CLUTCH HAVING LOCKUP FLUID OPERATED MEANS ENGAGEABLE TO CONNECT SAID INPUT AND OUTPUT MEMBERS, AND A MULTIRATIO GEAR UNIT HAVING FIRST AND SECOND SPEED RATIO FLUID OPERATED MEANS OPERABLE, ON THE SUPPLY OF FLUID, TO SELECTIVELY ENGAGE A FIRST AND SECOND SPEED RATIO CONNECTED IN SERIES; A SOURCE OF FLUID UNDER PRESSURE; LOCKUP CLUTCH CONTROL MEANS OPERABLY CONNECTED TO SAID SOURCE AND SAID LOCKUP FLUID OPERATED MEANS OPERABLE TO CONNECT SAID SOURCE FOR FLOW TO SAID LOCKUP FLUID OPERATED MEANS; RATIO CONTROL MEANS INCLUDING A RESTRICTION OPERABLY CONNECTING SAID SOURCE TO SAID FIRST AND SECOND RATIO FLUID OPERATED MEANS TO CONNECT SAID SOURCE FOR FLOW THROUGH SAID RESTRICTION, PROVIDING A HIGHER DIFFERENTIAL PRESSURE ON THE UPSTREAM SIDE OF SAID RESTRICTION AND A LOWER PRESSURE ON THE DOWNSTREAM SIDE OF SAID RESTRICTION, SELECTIVELY TO SAID FIRST AND SECOND RATIO FLUID OPERATED MEANS TO SELECTIVELY ENGAGE SAID FIRST AND SECOND SPEED RATIOS OF SAID MULTIRATIO GEAR UNIT, LOCKUP CUTOFF CONTROL MEANS OPERATIVELY 